I've discussed these questions in the past here (Kauai thread maybe?). Everything has a clear answer - but one should always do as their LOR says. A LOR who doesn't know the answer will hopefully say so and/or ask someone who does.
Sadly, this is not always the case. I learned this the hard way.
Just like many Doctors won't admit they don't know something (in their field) and refer to you to someone else, so do Rabbanim.
It is very easy to take the "machmir" approach.
As I once heard many years ago it doesn't take a "big lamden" to be machmir, rather the opposite.